GitHub does this too, and it's awful. Why would anyone want to skip reviewing the biggest changes?
'Cuz yeah, I've seen some nasty stuff sail past code review simply because it's so easy to accientally miss those files.
I feel like everything about the GitHub PR UI is targeted at reducing the code review job to being a human style checker. Minimal context, no code navigation, abysmal rename following.. it's really hard to review the design of a change.
Though it can certainly hide much more relevant-to-reviewers changes easily.